Types: Adds type safety to appEvents (#19418)

* Types: Add type safety to appEvents

packages/grafana-data/src/types/appEvent.ts

@@ -0,0 +1,4 @@
+export interface AppEvent<T> {
+  readonly name: string;
+  payload?: T;
+}

packages/grafana-data/src/types/events.ts

@@ -0,0 +1,7 @@
+import { eventFactory } from './utils';
+
+export type AlertPayload = [string, string?];
+
+export const alertSuccess = eventFactory<AlertPayload>('alert-success');
+export const alertWarning = eventFactory<AlertPayload>('alert-warning');
+export const alertError = eventFactory<AlertPayload>('alert-error');

packages/grafana-data/src/types/index.ts

@@ -13,3 +13,7 @@ export * from './graph';
 export * from './ScopedVars';
 export * from './transformations';
 export * from './vector';
+export * from './appEvent';
+
+import * as AppEvents from './events';
+export { AppEvents };

packages/grafana-data/src/types/utils.ts

@@ -1,2 +1,14 @@
+import { AppEvent } from './appEvent';
+
 export type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;
 export type Subtract<T, K> = Omit<T, keyof K>;
+
+const typeList: Set<string> = new Set();
+export function eventFactory<T = undefined>(name: string): AppEvent<T> {
+  if (typeList.has(name)) {
+    throw new Error(`There is already an event defined with type '${name}'`);
+  }
+
+  typeList.add(name);
+  return { name };
+}